This is a movie about a slasher murderer guy who ends up being the village idiot or a fat Forrest Gump type. The only major sick parts I remember was when this couple is getting ready to have sex (or something). The lady is all kinked out in a black bra and black panties, she has red or brown curly hair, while the guy is blonde and he is in the upstairs bedroom painting makeup around his eyes for some reason. The killer ties the lady up, tapes her mouth shut, and ties her to a tablesaw in the basement and arranges it so that the sawblade is digging into the small of her back, then rigs the tablesaw to the light switch at the top of the stairs heading into the basement, then leaves her there.

The blonde boyfriend upstairs gets done doing whatever he was doing in the bedroom and goes downstairs to look for the lady that he's going to do it with. He starts checking the house, then in the process checks the basement by turning the light on at the top of the stairs heading into the basement, which switches on the tablesaw and subsequently saws the lady that is tied to it, killing her. Unknown to the boyfriend, who heads back and searches the rest of the house or something, before getting an icepick or a knife into his ear by the killer.

SPOILER: The Forrest Gump killer is not killed at the end of the movie. Instead he is seen riding away on his bicycle whistling his little retarded tune, destined to kill again in a society that dismisses him for being a retard. At least, that was the lesson that my little 8 or 9-year-old mind learned from this dumb movie. Damned if I can remember what the title was though, because I only saw it once when we rented it from the video store in 1983 (I got that year right, at least).

A scene kind of like that occurs in Bloody Moon. The killer also turns out to be someone everyone thought was retarded. It's been awhile since I've seen it so I can't remember if he actually was or was just pretending.

I'm going off of literally a 30-year-old memory of this movie. Frankly, in my ripe old age of 39 years, I'm amazed that I still remember this one. I might have gotten the sequence of events muddled regarding those two unfortunate victims, but I definitely remember the ending. You are probably correct about people thinking that the guy was retarded, since it took a stroke of genius to connect the power between the tablesaw and the light switch. Thanks for providing a title though, that's a good place to start!

The scene you described is from the movie Savage Weekend (1979). I don't know where you got the fat guy from, perhaps another movie, but the Forrest Gump type they suspect is the killer is William Sanderson, perhaps best known as Larry of Larry, Darryl and Darryl on Newhart.

I read some of the IMDB reviews on that movie. I also did a Metacrawler search and found a picture of the scene that looks pretty close to the scene that I was talking about, so that might be it. I don't know, the mask made him look fat to me in 1983. I'm pretty sure that I only saw the film once. I'll have to track the movie down and see if that's the one that I saw, or if I was confusing two movies together.